1. Field of the Invention
This invention relates to a novel 2'-deoxy-5-fluorouridine derivative represented by the general formula (I); ##STR2## wherein R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an acetyloxy group or a halogen atom, and n is an integer of 1 to 3, and to a process for producing the same, and further to an antitumor agent comprising the same as an active ingredient.
2. Description of the Prior Art
2'-Deoxy-5-fluorouridine (hereinafter referred to as "FUDR") is a compound used as an antitumor agent. However, FUDR is potentially a highly toxic drug with a narrow margin of safety. In addition, the administration route of FUDR is limited to the intra-arterial injection, that is, FUDR cannot be medicated by an oral route. This is definitely limiting to the clinical therapy [Physicians' Desk Refernece, 1387, (1978)].
C. Heidelberger el al have made an energetic study on the action mechanism of FUDR and have examined a variety of FUDR derivatives obtained by chemical modification of FUDR in order to make an improvement on the above defects and endow a greater antitumor effect.
As a result, it has been suggested that 2'-deoxy-3',5'-di-O-acetyl-5-fluorouridine (hereinafter referred to as "acetyl FUDR"), which is one of the FUDR derivatives synthesized by C. Heidelburger et al., may not be degraded easily in vivo when medicated orally [Cancer Research 23, 49(1963)]. However, the experimental results on the antitumor activity show that acetyl FUDR is nearly equal to, or may be less effective than FUDR [Biochemical Pharmacology 14, 1605(1965); Cancer Research 23, 420(1963)].
The results obtained by many studies on the FUDR derivatives are summarized in Cancer Research [30, 1555-1556(1970)] in terms of the relationships between the chemical structures of FUDR and derivatives thereof and the antitumor activities.
In this literature there is provided an illustration which indicates what type of groups at any position in the FUDR molecular structure is indispensable in manifestation of the antitumor effect, using, as an indicator, the three key enzymatic activities which have been found to be involved in the mechanism of the anticancer action of the FUDR derivatives. And there can be found an express mention that the nitrogen atom at the 3-position on the pyrimidine ring should not be substituted.
The present inventors have made an energetic study on acetyl FUDR derivatives in order to enhance their antitumor activities and to lower their toxicity, and as a result, have found, in contrast to the above conclusion, that a novel compound represented by the general formula (I) possesses a desirable effect, which is substituted at the nitrogen atom at the 3-position on the pyrimidine ring by a specified aroyl group.